The invention relates to a corona ignition device for igniting fuel in a combustion chamber of an engine by means of a corona discharge.
Corona ignition devices are an alternative to spark plugs, which ignite fuel as a result of an arc discharge. Corona ignition devices by contrast cause an ignition by means of a corona discharge and therefore have the potential of a much longer service life. Corona discharges specifically cause much less burn-up at an ignition tip compared to arc discharges.
Corona discharges at an ignition tip are generated by high-frequency excitation of an electric resonating circuit. The capacitor of this resonating circuit is formed by the housing of the corona ignition device and a central electrode, which leads to the ignition tip. The central electrode sits in a channel of an insulator, which closes the combustion-chamber-side end of the housing in a gas-tight manner. A glass seal is located in the channel of the insulator in order to prevent leaking of combustion chamber gases.
A frequent cause of premature failure of corona ignition devices is a dielectric breakdown inside the corona ignition device.